Oil extraction apparatus



June 27, 1961 R. R. MICKUS ET AL OIL EXTRACTION APPARATUS 2 Sheets-Sheet 1 Filed April 22, 1955 INVENTORS ROBERT P. MIC/(US GEORGE W BREWER By /Z1%/ w,

ATTORNEYS R. R. MICKUS ETAL OIL EXTRACTION APPARATUS June 27, 1961 2 Sheets-Sheet 2 Filed April 22, 1955 INVENTORS ROBERT R- M/C/(US GEORGE W BREWER ggoym m a-lfazmL A T TORNE VS 2,990,255 OIL EXTRACTION APPARATUS Robert R. Mickus and George W. Brewer, Sacramento,

assignors to Rice Growers Association of Caliorma Filed Apr. 22, 1955, Ser. No. 503,239 4 Claims. c1. 23-272 This invention relates to an apparatus and method for extracting oil from finely divided solid material. The invention will be described in connection with the extraction of oil from rice bran, but it will be understood that it is equally applicable to other similar materials containing oil.

The by-product of the operation of milling rice is rice bran and polish, which contains a high grade edible oil very similar to cottonseed, soybean and peanut oil. Attempts have been made in the past to extract oil in an economical manner from rice bran through the use of conventional oil expelling or extraction methods. These prior attempts have been, for the most part, unsuccessful, partly because of the relatively low yield that has been effected and partly because of the lack of efiiciency which has attended such methods.

Continuous extraction methods have heretofore been unsuccessful because the comminuted bran is extremely fine and is therefore difiicult to remove from the oil.

By the present invention a batch process is used which has the advantages of low initial investment, flexibility with regard to tonnage processed and the simplicity of the apparatus required.

However, even by the batch method, the problem of removing the extremely fine particles of bran from the oil is still present and greatly complicates the operation. In this connection, it should be noted that during the rice milling operation the bran is pulverized to such an extent that 25 percent of the same passes through a 100 mesh (Tyler) screen and only percent is retained on an 18 mesh screen.

It has been suggested in the past to mix solvent with the comminuted bran and strain the mixture through a very fine canvas or the like having openings small enough to prevent passage of the smallest particles. Such attempts have failed because of the inordinate length of time required to remove the miscella, that is, the solution of solvent and oil, from the mixture. If a screen is employed of a sufliciently course mesh to pass the solution in a reasonable length of time the fines of the bran will also pass and it is next to impossible to subsequently separate them from the solution. Even when canvas is employed the length of time required to drain the miscella cannot be accurately predetermined.

To be successful, as a practical matter, an extraction process such as herein contemplated must lend itself to fairly accurate time scheduling and it is therefore the most important object of this invention to provide a process of oil extraction which may be carried out under predetermined operational conditions and provide uniformity of product.

Another object of the invention is the provision of an oil extraction process for rice bran that extracts an optimum amount of oil from the bran. In this connection it is of interest to note that, although Japan has recently produced about 17,000 tons of rice bran oil per year, it has been found that the bran retains about 50 percent of the oil after the extraction process.

In this country the extracted bran has been found desirable for animal feed, but for this purpose substantially all of the oil should be extracted. When so extracted, by one method of the present invention, the bran is more desirable for feeds because of its high protein concen- Patented June 27, 1961 tration resulting from the removal of the lipid portion of the bran.

Before describing the invention in detail, the general method of operation will be reviewed to point up the salient points, involved.

Rice bran received from the mill in its finely divided state after removal of the grain is batch extracted using hexane (C H as the solvent. The hexane is sprayed into a batch of bran under predetermined temperature conditions and proportions and is permitted to percolate through the mass of bran and drain therefrom. The solvent passing through the bran strips out the oil which is extremely soluble in hexane and is collected through a piping system in large miscella receiving vessels.

The solvent laden extracted bran is then dried to remove the solvent and is packaged. The miscella, or mixture of solvent and oil is then heated and evaporated by conventional processes to free the oil of the hexane.

The present invention concerns only the process of extracting the oil from the bran and is not concerned with the subsequent operations of drying the extracted bran and removing the hexane from the solution of hexane and oil through these steps are essential to complete the oil extraction. However, as an incident to the subsequent recovery of the oil, it will be understood that the removal of fine particles of bran from the miscella presents a serious problem. It is for this reason it is important to prevent such fine particles from being drained with the solution from the batch of bran.

In the drawings:

FIG. 1 is a top plan view of the extractor tank of the present invention with portions of the top of the tank and auxiliary equipment broken away and in section to show internal structure.

FIG. 2 is an end elevation of the tank partially broken away and in section to show internal structure.

FIG. 3 is greatly enlarged fragmentary section through the tank as taken along lines 33 of FIG. 1.

In detail, the apparatus of the present invention comprises a relatively large tank generally designated I having a top 2 and vertical sidewalls 3. The tank I may be divided into two or more large compartments by an inner bulkhead 4 (FIGS. 1, 3) although the internal construction is not critical except in the respects hereinafter noted.

The bottom of the tank 1 on which the bran rests consists of one or more panels of relatively fine stainless steel screen generally designated 5 (FIG. 3). To prevent the Weight of the solvent soaked bran from being taken by the screen 5 a fiat bar grid 6 may be provided just under the screen 5. The structural bottom 7 of the tank 1 is provided with one or more apertures 8 communicating with the miscella piping system, the intake end of a portion of which is indicated at 9. It will be understood, of course, that the present invention is not primarily concerned with the subsequent operations on miscella.

The screen 5 is supported on a peripherally extending gasket strip 10 which in turn may be carried by a leg of a structural bounding angle 13. On top of the marginal portions of screen 5 is another gasket strip 14. Bolts 15 extend through the gaskets 1t), 14 and are secured to the angle 13 to provide a tight joint preventing escape of fine particles of bran therethrough.

Bran to be extracted may be brought to the tank 1 by any conventional means such as a screw conveyor and is dumped into the tank through spouts 16, 17 (FIG. 2). When the tank 1 is substantially filled with bran, hexane is sprayed onto the bran through a piping system provided with suitable apertures or orifices. To this end a coil of pipe 18 is hangered to the upper corners of the tank and is connected to a feed pipe 19 supplying the hexane from a suitable source (not shown). In most cases it is desirable to add sufficient solvent so that it establishes a level just above the mass of bran. Of course the hexane spray tends to level off the bran so that a uniform effect in all bran particles is achieved. It will be noted that a relatively heavy weight is thus imparted to thescreen 5 but the grid 6 resists this weight which has the additional effect of enhancing the seal provided by the gasket 10. It has been found that a time interval of roughly five to six hours permits sufiicient time for drainage through the screen 5.

The next step is to remove the still moist extracted bran and this is done by means of a plurality of screw conveyors 20. Conveyors may be arranged in two flights as shown in FIG. 2 and are provided with shafts 21 extending through one side of the tank 1 and supported on bearings 22. Suitable stuffing boxes 23 are provided on the tank to prevent leakage past the shafts 21. At the outer end of each shaft 21 sprocket wheels 25 are provided and the conveyors may be driven through a sprocket chain 26 in opposite directions in the manner shown in FIG. 2. Sprocket chain 26 is connected with a suitable source of power such as the sprocket wheel 28 onthe output shaft of a reduction gear 29 driven by an electric motor 30.

At the opposite ends of screw shafts 21 the same are rotatably carried in bearings 32 suitably supported internally of the tank 1. The adjacent sidewall 3 of the tank 1 is provided with a relatively large rectangular opening 33 (FIGS. 1, 3) through which the extracted bran is discharged.

A cover plate 34 provided with a peripherally extending gasket 35 seals the opening 33 and is supported adjacent its opposite ends on horizontal guide rods 36, 37 which in turn extend through a discharge box generally designated 40. Box 40 is provided with inspection doors 41 (FIG. 1) and carries suitable sleeves '43, '44 in which guide rods 36, 37 are reciprocable.

Secured centrally to the outer side of cover plate 34 by means of a swivel joint 45 is one end of a screwthreaded shaft 46 that is received in an internally threaded nut 47 fastened to the outer side of discharge box 40. A handwheel 48 is provided on the outer end of shaft 46 for turning the latter for urging the cover plate 34 toward or away from the discharge opening 33 in tank 1. During the extraction process the cover plate 34 is, of course, in sealing engagement with the adjacent sidewall 3 of tank 1, but when it is desired to remove the extracted bran, the cover plate 34 is moved outwardly by turning handwheel 48.

Under the box 40 is a screw conveyor generally designated 50 into which the extracted bran falls. Conveyor 50 is driven in the conventional manner through a reduction gear 51 from a motor 52.

Although the extracted bran tends to adhere together in a pile, upon actuation of the screw conveyors 20 within tank 1, the bran is fed outwardly from the bottom of the tank and in due time substantially all of the bran has fallen down into a position to be acted upon by the conveyors 20 resulting in an almost complete discharge of the contents of the tank.

An important feature of the present invention resides in the fact that a bed of extracted bran 55 is always permitted to remain on the screen 5. As best seen in FIG. 3, the bottom sides of the screw conveyors 20 are slightly spaced upwardly from the screen 5 so that the bran immediately above the screen 5 is never discharged, butremains to act as a filter which, in addition to permitting draining of the miscella in a predeterminable length of time, prevents the passage therethrough of the fines.

The screen 5 is preferably 100' mesh which ordinarily would permit about 25 percent of the bran to pass through. However, once a bed of bran is established as shown in FIG. 3, substantially all of the bran, including thefines, is retained .in the-bed of bran- It will be understood that until a bed of bran is established on the screen 5, the desired filtering effect will not be obtained. Thus, when the screen 5 is clean, special disposition is made of the miscella passing therethrough and the same is not permitted to enter the regular receiving tanks until the filtering action of the bed of bran on the screen 5 becomes efiective. However, the bed of bran may remain on the screen 5 during many batch extraction processes before cleaning of the screen is desirable.

It will be understood, of course, that after the conveyors 20' have discharged the batch of bran except for the bed 55, the cover plates 34 are sealed against the tank and another batch of bran is dumped into the tank 1 through the spouts 16, 17 and the soaking and draining steps are repeated. However, upon subsequent discharge of the oil extracted batches of bran, the bed 55 remains undisturbed.

We claim:

1. Apparatus for extracting oil from rice bran and the like, comprising: a tank, a liquid pervious support extending horizontally in said tank for supporting thereon a batch of bran, said tank being provided with an opening above said support for discharging bran into said tank and onto said support, solvent discharge means above said support for soaking said batch with solvent whereby the oil in said bran is dissolved in said solvent and the solution of oil and solvent drains through said support, means operative across substantially the entire width of said tank at said support for horizontally discharging substantially all of said batch from said support except for a bed of bran adjacent said support, whereby said bed remains undisturbed upon operation of said means, said means comprising a conveyor adjacent to but spaced upwardly from said support to provide a space extending longitudinally of said conveyor between the lowermost point of said conveyor and said support.

2. Apparatus for extracting oil from rice bran and the like, comprising: a tank, a screen extending horizontally in said tank for supporting thereon a batch of bran, said tank being provided with an opening above said screen for discharging bran into said tank and onto said screen, solvent discharge means above said screen for soaking said batch with solvent whereby the oil in said bran is dissolved in said solvent and the solution of Oil and solvent drains through said screen, means operative across substantally the entire width of said tank at said support for horizontally discharging substantially all of said batch from said screen except for a bed of bran adjacent said screen, whereby said bed remains undisturbed upon operation of said means, said means comprising a conveyor adjacent to but spaced upwardly from said screen to provide a space extending longitudinally of said conveyor between the lowermost point of said conveyor and said screen, said tank being provided with an opening in one side thereof through which bran is discharged from said tank upon actuation of said conveyor, cover means for sealing said opening when said conveyor is inoperative, and means for removing said cover means to permit discharge of said bran when said conveyor is operative.

3. Apparatus for extracting oil from rice bran and the like, comprising: a tank, a screen extending horizontally in said tank for supporting thereon a batch of bran, said tank being provided with an opening above said screen for discharging bran into said tank and into said screen, solvent discharge means above said screen for soaking said batch with solvent whereby the oil in said bran is dissolved in said solvent and the solution of oil and solvent drains through said screen, means operative across substantially the entire width of said tank at said support for horizontally discharging substantially all of said batch from said screen except for a bed of bran adjacent said screen, whereby said bed remains undisturbed upon operation of said means, said means comprising a conveyor adjacent to but spaced upwardly from said screen to provide a space extending longitudinally of said conveyor between the lowermost point of said conveyor and said screen, said tank being provided with an opening in one side thereof through which bran is discharged from said tank upon actuation of said conveyor, cover means for sealing said opening when said conveyor is inoperative, and means for removing said cover means to permit discharge of said bran When said conveyor is operative.

4. Apparatus for extracting oil from rice bran and the like, comprising: a tank, a screen extending horizontally in said tank for supporting thereon a batch of bran, said tank being provided with an opening above said screen for discharging bran into said tank and into said screen, solvent discharge means above said screen for soaking said batch with solvent whereby the oil in said bran is dissolved in said solvent and the solution of oil and solvent drains through said screen, means operative across substantially the entire width of said tank at said support for horizontally discharging substantially all of said batch from said screen except for a bed of bran adjacent said screen, whereby said bed remains undisturbed upon operation of said means, said means comprising a conveyor adjacent to but spaced upwardly from said screen to provide a space extending longitudinally of said conveyor between the lowermost point of said conveyor and said screen, said tank being provided with an opening in one side thereof through which bran is discharged from said tank upon actuation of said conveyor, cover means for sealing said opening when said conveyor is inoperative, and means for removing said cover means to permit discharge of said bran when said conveyor is operative, said conveyor comprising a plurality of parallel screw members in side by side relationship to provide for uniform discharge of said bran across substantially the entire area of said screen.

References Cited in the file of this patent UNITED STATES PATENTS 203,981 Adawson et al May 21, 1878 491,370 McCarty Feb. 7, 1893 637,465 Hutchinson Nov. 21, 1899 1,905,781 Allington Apr. 25, 1933 2,066,479 Macisaac Jan. 5, 1937 2,203,666 Bonotto June 11, 1940 2,451,081 Ford Oct. 12, 1948 2,484,831 Hutchins et a1. Oct. 18, 1949 2,517,040 Simon Aug. 1, 1950 2,608,565 Bonnoto Aug. 26, 1952 2,641,536 Upton June 9, 1953 2,727,914 Gastrock et al Dec. 20, 1955 FOREIGN PATENTS 1,550 Great Britain Jan. 21, 1909 OTHER REFERENCES 30 pages 172 and 173. 

1. APPARATUS FOR EXTRACTING OIL FROM RICE BRAN AND THE LIKE, COMPRISING: A TANK, A LIQUID PERVIOUS SUPPORT EXTENDING HORIZONTALLY IN SAID TANK FOR SUPPORTING THEREON A BATCH OF BRAN, SAID TANK BEING PROVIDED WITH AN OPENING ABOVE SAID SUPPORT FOR DISCHARGING BRAN INTO SAID TANK AND ONTO SAID SUPPORT, SOLVENT DISCHARGE MEANS ABOVE SAID SUPPORT FOR SOAKING SAID BATCH WITH SOLVENT WHEREBY THE OIL IN SAID BRAN IS DISSOLVED IN SAID SOLVENT AND THE SOLUTION OF OIL AND SOLVENT DRAINS THROUGH SAID SUPPORT, MEANS OPERATIVE ACROSS SUBSTANTIALLY THE ENTIRE WIDTH OF SAID TANK AT SAID SUPPORT FOR HORIZONTALLY DISCHARGING SUBSTANTIALLY ALL OF SAID BATCH FROM SAID SUPPORT EXCEPT FOR A BED OF BRAN ADJACENT SAID SUPPORT, WHEREBY SAID BED REMAINS UNDISTURBED UPON OPERATION OF SAID MEANS, SAID MEANS COMPRISING A CONVEYOR ADJACENT TO BUT SPACED UPWARDLY FROM SAID SUPPORT TO PROVIDE A SPACE EXTENDING LONGITUDINALLY OF SAID CONVEYOR BETWEEN THE LOWERMOST POINT OF SAID CONVEYOR AND SAID SUPPORT. 